JP2005221091A - Radiator and forming method of heat receiving unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radiator, reducing change in configuration of a radiator to the utmost, hardly influenced by electrolytic corrosion that causes metal ions to dissolve in cooling water, and a forming method of a heat receiving unit constituting the above radiator. <P>SOLUTION: In a water-cooled radiator 1, a LD (laser diode) array 200, which is a heating unit, is installed, and the LD array 200 is cooled by cooling water 900 flowing through a passage 2 formed in the interior thereof. The radiator 1 includes a protective layer (a titanium oxide layer) 3 covering the surface of the passage forming surface (the surface) of the passage 2 in the radiator 1 to electrically insulate the cooling water 900 from the radiator 1. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a liquid-cooled radiator that cools a radiator such as a semiconductor laser diode (hereinafter simply abbreviated as LD) array, and a method for forming a heat receiver that constitutes the radiator.

In general, a high-power LD is used as an LD array mounted together with other components. Since this LD has a heat generation density as high as several tens to several hundreds W / cm ^{2, the} temperature of the entire LD array rises, and the laser output, efficiency, transmission wavelength, and element life of the LD are greatly affected. Therefore, how to remove heat from the LD array is a very important issue.

As such a heat countermeasure, for example, use of a radiator can be considered. A radiator is attached in contact with the LD array to efficiently radiate heat.
However, the contact surface of the LD array that comes into contact with the radiator is, for example, about 10 mm in width and about 1 to 1.5 mm in length, and the contact area with the radiator is very small. For this reason, with a simple air-cooled radiator, the amount of heat generated by the LD exceeds the amount of heat released, and the temperature rise of the LD array could not be suppressed. In view of such circumstances, it is common to use a liquid-cooled (generally water-cooled) radiator having a flow path therein as an LD array radiator.

  The heat dissipation of the LD array according to this prior art will be outlined. FIG. 12 is a schematic system configuration diagram of the LD array heat dissipation system. The LD array heat dissipation system includes a radiator 100, an LD array 200, a power supply device 300, a water supply / drain manifold 400, a flow channel 500, a tank 600, a flow channel 700, and a pump 800, and includes cooling water (specifically pure water). ) 900 is a circulating system.

  In this system, an LD array 200 on which a high-power LD (not shown) is mounted is joined by a brazing material or the like and directly mounted on the radiator 100. The LD array 200 is configured such that power is supplied through a path of the power supply device 300 → the radiator 100 → the LD array 200 → the LD, and the LD in the LD array 200 emits light. Since such a high output LD is applied with a power of 40 to 100 W per one, this large power is also applied to the inside of the radiator 100 and the current i flows.

  Further, in this system, a circulation system for supplying and discharging the cooling water 900 to and from the radiator 100 is formed, and the cooling water 900 in the tank 600 is transferred from the flow path 700 to the pump 800 to the supply and drainage manifold 400 by the pump 800. 400a → the flow path 101 of the radiator 100 → the flow path 400b of the water supply / drainage manifold 400 → the flow path 500 circulates. At this time, the LD array 200 is cooled by heat conduction through a path from the LD array 200 to the radiator 100 to the cooling water 900 in the flow channel 101.

  Subsequently, the details of the structure of the radiator 100 will be schematically described. FIG. 13 is a cross-sectional view taken along the line P-P of the radiator. 14 is a cross-sectional view of the radiator, FIG. 14 (a) is a cross-sectional view taken along the line A-A, FIG. 14 (b) is a cross-sectional view taken along the line BB, and FIG. 14 (c). These are C arrow directional views of a CC line cross section. FIG. 15 is a cross-sectional view of the radiator, FIG. 15 (a) is a view taken along the line Q-Q before joining, and FIG. 15 (b) is a view taken along the line Q-Q after joining. It is.

The radiator 100 is a radiator for a high-power LD array, and employs a three-layer structure in which a plate-like lower heat receiving body 110, a middle heat receiving body 120, and an upper heat receiving body 130 are stacked as shown in FIG. ing. The lower heat receiving body 110, the middle heat receiving body 120, and the upper heat receiving body 130 are all manufactured using a metal material having good heat conduction.
The lower heat receiving body 110 includes a water supply port 111, a heat radiating fin 112, a lower surface water channel 113, a flow path restricting portion as shown in the top view of the lower heat receiving body 110 viewed from the direction of arrow C in FIG. 13 and FIG. 14 (c). 114 and a drainage port 115. Note that the stippled portion is not penetrating, that is, a hole with a bottom.
The intermediate heat receiving body 120 has a circular communication hole 121, a circular communication hole 122, a partition wall 123, and a through hole 124 as shown in the top view of the intermediate heat reception body 120 viewed from the direction of arrow B in FIG. 13 and FIG. , An upper spot facing part 125 and a lower spot facing part 126 (see FIG. 13). The stippled area represents a hole with a bottom.
The upper heat receiving body 130 includes a water supply port 131, an upper surface water channel 132, and heat radiating fins 133 as shown in the bottom view of the upper heat receiving body 130 as viewed from the direction of arrow A in FIG. 13 and FIG. The stippled area represents a hole with a bottom.
As shown in FIG. 15A, diffusion bonding, solder, or the like sandwiching a brazing material sheet (not shown) with respect to the lower heat receiving body 110, the middle heat receiving body 120, and the upper heat receiving body 130 before bonding, as shown in FIG. ) In a state in which the airtightness is maintained as shown in FIG. By such joining, a flow path communicating with the lower heat receiving body 110, the middle heat receiving body 120, and the upper heat receiving body 130 as shown in FIGS. 15A and 15B is formed. Although not shown, a thin bonding layer is formed on the bonding surface.

  Next, the flow of cooling water in the radiator 100 having such a configuration will be described. As shown in FIG. 13, the LD array 200 is joined to the upper heat receiving body 130 on the upper side of the radiation fins 133. As shown in FIG. 13, the cooling water 900 is guided from the flow path 400 a to the water supply port 111 of the lower heat receiving body 110, passes through the circular communication port 121 of the middle heat receiving body 120 as it is, and the water supply port of the upper heat receiving body 130. Reach up to 131. The upper surface water channel 132 of the upper heat receiving body 130 is a channel having an enlarged area, and the cooling water 900 also has an enlarged area and reaches the radiation fins 133. At this time, in order to reduce the pressure loss on the water supply side, the upper counterbore 125 is provided in the intermediate heat receiving body 120 just before the heat radiation fins 133 to enlarge the cross-sectional area of the flow path, and the cooling water 900 flows into the heat radiation fins 133. At this time, the heat exchange efficiency is improved by increasing the flow rate.

  The cooling water 900 that has reached the radiating fins 133 exchanges heat between the high heat of the LD array 200 and the low heat of the cooling water 900 between the radiating fins 133 and the cooling water 900, so that the circular communication port 122 of the intermediate heat receiving body 120 is exchanged. It passes between the radiation fins 112 provided on the street lower heat receiving body 110 and reaches the lower surface water channel 113. Here, the cooling water 900 is divided into two by the flow path narrowing portion 114, merged again at the drainage port 115, and discharged outside the radiator 100. At this time, in order to reduce the pressure loss, the lower counterbore 126 (see FIG. 13) is provided on the intermediate heat receiving body 120 on the rear side of the radiating fin 113 to enlarge the cross-sectional area of the flow path. Similarly, in order to reduce the pressure loss of the drain port 115, the through-hole 124 is provided in the intermediate heat receiving body 120 to increase the cross-sectional area of the flow path.

In this heat radiator 100, the heat radiation fin 133 is characterized in order to enhance the cooling effect. The radiating fins 133 of the radiator 100 are provided below the position where the LD array 200 is attached. The heat generated by the LD array 200 is radiated by the upper heat receiving body 130 and is thermally conducted in the thickness direction. The heat radiating fins 133 are designed to have a length several times that of the radiating fin 133.
Since the cooling water 900 is in contact with the numerous radiating fins 133, heat exchange is performed efficiently. However, since the heat radiation amount is not sufficient only by the heat radiation fins 133 provided on the upper heat receiving body 130, heat conduction is performed to the partition wall 123 of the middle heat receiving body 120, and heat conduction is further performed to the heat radiation fins 112 provided on the lower heat receiving body 110. The structure increases the amount of heat (see FIGS. 14 and 15).
Due to such a configuration, the radiator 100 increases the heat radiation amount. The prior art was like this.

  Further, as another heat radiator of the prior art, for example, the invention described in Patent Document 1 is known. The cooling device described in Patent Document 1 is also a cooling device for cooling a laser diode, and is manufactured by laminating metal sheets in multiple layers.

Japanese Patent Laid-Open No. 10-209531 (paragraph numbers 0036 and 0038, FIG. 1)

The prior art radiator 100 described with reference to FIGS. 12 to 15 is electrically connected to the radiator 100 to supply power to the LD mounted on the LD array 200, and the power supply path is in the radiator 100. Is formed. A maximum of 1000 W of power is applied to the LD, and the current i flows through the heat sink 100 as well, for example, as shown by a dashed line in FIG. 12, and an electric field is applied to the heat sink 100. . Further, the radiator 100 and the cooling water 900 are in direct contact. In this case, the metal which is the material of the radiator 100 touches the electrolyte such as water, and metal ions are dissolved in the cooling water 900 due to the ionization tendency. In addition, since a large electric field is applied to the inside of the radiator 100 as described above, the dissolution of metal ions is accelerated to cause an electrolytic corrosion phenomenon.
In the prior art, in order to improve heat conduction, copper material is used as the material of the radiator 100. In addition, when the radiator 100 is manufactured, the radiator 100 is not subjected to surface treatment in order to keep the manufacturing cost low. Since bonding is performed by bonding or the like, the ionization tendency is increased, and corrosion due to electrolytic corrosion occurs as described above.

In addition, as shown in FIG. 12, in the LD array heat dissipation system, cooling water 900 flows also in other metal parts such as a metal water supply / drainage manifold 400, and these metal parts are electrically connected to the LD power supply device 300. In many cases, GND is common.
Since the cooling water 900 uses pure water having an electric resistance of 1 MΩ · cm or more, the phenomenon of electrolytic corrosion is unlikely to occur, but as time passes, the electric resistance decreases due to the metal ions dissolved in the cooling water 900. When the metal flows easily, the metal parts are installed in the GND, and therefore, when passing through the radiator 100, an electric field is applied to the cooling and the melting of the metal ions from the radiator 100 becomes intense.

In particular, the radiation fins 133 are mounted directly under the radiator 100 mounting the LD array 200 on which the LD is mounted. However, since the flow speed of the cooling water 900 is high in this portion, corrosion due to electrolytic corrosion is particularly severe. When the phenomenon that the fins 133 are completely melted occurs, the cooling cannot be performed, and the temperature rise of the LD is remarkably increased, and the LD may be damaged.
This type of radiator 100 is also used to increase the heat dissipation effect by stacking several tens of radiators 100 when increasing the output. In this case, since the LD supplies electric power to the series, a considerably large electric field is applied to the cooling water flowing in the uppermost radiator from the viewpoint of GND, and the problem of electrolytic corrosion becomes more important. However, the problem of electric corrosion has not been solved.

Further, the conventional technique has a problem in cooling characteristics.
In order to suppress the temperature rise accompanying the increase in output of the LD array 200, it is necessary to further increase the efficiency of heat exchange with the cooling water. FIG. 16 is a schematic diagram showing a flow state when cooling water is passed through the flow channel with the bare pipe wall exposed, and FIG. 16A is a schematic diagram of the flow channel cross-sectional area, FIG. ) Is a schematic diagram of a small channel cross-sectional area, and FIG. 16C is an enlarged view of the tube wall. FIG. 17 is an explanatory diagram for explaining the influence of power application, FIG. 17 (a) is a time-power diagram, and FIG. 17 (b) is an explanatory diagram for explaining the relationship between power and temperature.
As shown in FIG. 16A, when the cooling water 900 is caused to flow through the flow path 101, a flow velocity distribution is generated due to the pipe friction resistance of the pipe wall 101a and the viscosity of the fluid. This pipe frictional resistance increases the resistance of the fluid flowing through the channel 101, that is, the pressure loss. As shown in FIG. 16 (b), when the flow path cross-sectional area is reduced to increase the heat exchange performance (increase the flow velocity), the pressure loss significantly increases due to the effect of pipe frictional resistance.

Moreover, since the flow velocity in the vicinity of the tube wall 101a is small due to the tube frictional resistance, the heat resistance due to heat transfer from the radiator 100 main body to the fluid increases, and the heat exchange performance decreases.
Furthermore, when the wettability of the surface of the tube wall 101a is poor, when the tube wall 101a is enlarged as shown in FIG. 16C, the surface has minute unevenness, and the cooling water does not fit in the recessed portion. Layer 102 results. The air layer 102 becomes a heat insulating material, and the heat from the tube wall 101a is mainly transferred only from the convex portion, which causes a significant deterioration in heat exchange performance.

Further, as shown in FIG. 17A, in this type of radiator 100, the power applied to the LD is not continuous, but intermittent, such as a high-frequency pulse, and the application pattern is various.
In such a heat radiator 100 that is used, the heat flow is remarkably reduced because the flow velocity near the surface of the tube wall 101a is slow due to the influence of the tube frictional resistance of the tube and the wettability of the surface of the tube wall 101a is poor. When the performance is lowered, as shown in FIG. 17 (b), the heating response time from when the power application start time until the temperature rise of the radiator 100 becomes a stable state (steady state) becomes longer. Similarly, the cooling response time from when the power is interrupted until the temperature of the radiator 100 drops is also increased. If the heating or cooling response time is long, the transmission wavelength of the LD is directly affected, and if the ON / OFF cycle of the applied power is fast, the transmission wavelength is not stable.

  Further, these problems can occur even in the invention described in Patent Document 1, and countermeasures have been demanded.

  Therefore, the present invention has been made in view of the above-described problems, and the purpose thereof is to improve the cooling performance while minimizing the configuration, and further to the influence of electrolytic corrosion that metal ions dissolve into the cooling water. Another object of the present invention is to provide a heat sink that does not receive heat and a method of forming a heat receiver of the heat receiver that constitutes such a radiator.

In order to solve the above problems, a radiator of the invention according to claim 1 of the present invention provides:
In a liquid-cooled radiator in which a heating element is attached in contact with the outside and the heating element is cooled by a coolant flowing through a flow path formed on the inside,
A protective layer that covers the flow path forming surface inside the radiator and electrically insulates the coolant from the radiator,
It is characterized by providing.

Moreover, the radiator of the invention according to claim 2 of the present invention is
The heat radiator according to claim 1,
The protective layer is a titanium oxide layer that is electrically insulated and reduces frictional resistance.

Moreover, the radiator of the invention according to claim 3 of the present invention is
The heat radiator according to claim 1 or 2,
The heating element is a laser diode array on which a semiconductor laser diode that electrically connects the radiator as a part of a power supply path is mounted.

Moreover, the radiator of the invention according to claim 4 of the present invention is
In the heat radiator as described in any one of Claims 1-3,
The radiator is
A plate-shaped heat receiving body having a flow path forming surface on which a protective layer is formed, and a joint surface on which a ground metal appears other than the flow path forming surface;
A bonding layer bonded at the bonding surface of these heat receivers;
And having a structure in which a plurality of heat receiving bodies are joined and laminated by a joining layer to form a flow path covered with a protective layer.

Moreover, the radiator of the invention according to claim 5 of the present invention is
The heat radiator according to claim 4,
The bonding layer is a bonding layer formed by electrically, thermally, and mechanically bonding the bonding surfaces of the heat receiving bodies by a brazing material, a brazing material sheet, or diffusion bonding.

The method for forming the heat receiving body of the invention according to claim 6 of the present invention comprises:
A method for forming a heat receiving body constituting the radiator according to claim 4,
A heat receiving body forming step of forming a heat receiving body having a flow path forming surface and a joint surface other than the flow path forming surface;
A mask film coating process for coating a mask film on the entire surface of the heat receiver;
A resist coating step of coating a resist on the mask film on the surface including the flow path forming surface;
A resist exposure step of placing a mask on the resist and exposing the resist on the bonding surface;
A patterning development step of developing the resist and peeling off the resist on the flow path forming surface;
A mask film etching step for removing the mask film on the flow path forming surface and exposing the ground metal on the flow path forming surface;
A resist stripping process for stripping all resists;
A film forming step of forming a film on a surface including a flow path forming surface by a PVD method such as sputtering or ion plating, or a CVD method;
A mask film peeling step for peeling the mask film and forming a protective layer only on the flow path forming surface;
It is characterized by having.

  In the present invention, a protective layer (particularly a titanium oxide layer is preferable) is formed on the entire surface of the flow path of the radiator. This protective layer forming method uses a wet etching technique of silicon, forms a metal mask film only on the appearance and joint surfaces of a plurality of heat receiving bodies constituting a heat radiator, and forms a flow path forming surface of the heat receiving bodies. If a mask layer is removed after forming a protective layer on the entire surface including the surface of the heat-receiving body, there will be no protective layer on the heat receiving member bonding surface, and the ground metal will be exposed. In addition, it is possible to form a protective layer completely on the inclined surface of the flow path and up to the edge portion that is the boundary between the inclined surface of the flow path and the bonding surface. Joining is possible by forming a joining layer by joining with a material sheet or diffusion joining. In the radiator configured in this way, since the protective layer is formed up to the edge portion of the channel inclined surface of the channel forming surface, only the inside of the channel is completely covered with the protective layer at the time of joining. Insulates the heatsink electrically. In addition, the protective layer improves the wettability of the tube wall and enhances the heat cooling performance.

  According to the present invention as described above, it is possible to improve the cooling performance while minimizing the configuration as much as possible, and further to provide a radiator that is not affected by the electrolytic corrosion in which metal ions dissolve in the cooling water. It is possible to provide a method for forming the heat receiving body of the heat receiving body constituting the container.

Next, heat radiation of the LD array using the best mode heat radiator for carrying out the present invention will be schematically described with reference to the drawings. FIG. 1 is a schematic system configuration diagram of an LD array heat dissipation system including a heat radiator of the present embodiment. The LD array heat dissipation system includes a radiator 1, an LD array 200, a power supply device 300, a water supply / drain manifold 400, a flow path 500, a tank 600, a flow path 700, and a pump 800, and the cooling water 900 circulates. .
Although the radiator 1 is new in this system, other configurations, the cooling water circulation system, and the like are the same as those in the prior art, and are given the same reference numerals as in FIG.
The point that the protective layer 3 is formed on the entire surface of the flow path 2 of the radiator 1 is a novel point. Electrical protection is ensured by the protective layer 3 interposed at the interface between the radiator 1 and the cooling water 900. For this reason, when the LD is energized, a power path is formed by the radiator 1 between the LD array 200 and the power supply device 300, and even if a large electric field is applied due to the power supply, the protective layer 3 is electrically connected to the cooling water 900. Since no path is formed, metal ions do not dissolve from the radiator 1 to the cooling water 900 due to electrolytic corrosion. The protective layer 3 can be appropriately employed as long as electrical insulation can be ensured.
In such a radiator 1, the occurrence of electrolytic corrosion is suppressed.

  The protective layer 3 is particularly preferably a protective layer (titanium oxide layer) made of titanium oxide that is electrically insulated and has higher wettability than the ground metal of the pipe wall of the flow path 2 to reduce pipe frictional resistance. The reason for employing this titanium oxide protective layer will be described. FIG. 2 is a schematic diagram showing a flow state when cooling water is passed through a flow channel having a titanium oxide layer formed on the tube wall, and FIG. 2 (a) is a schematic diagram of the cross-sectional area of the flow channel. 2 (b) is a schematic diagram of a small channel cross-sectional area, and FIG. 2 (c) is an enlarged view of the tube wall.

  When titanium oxide is irradiated with ultraviolet rays as a photocatalyst, the superhydrophilic effect is improved. Such an effect is a permanent effect once irradiated with ultraviolet rays. When the radiator 1 is formed after the protective layer (titanium oxide layer) 3 formed by film formation in the flow path 2 is irradiated with ultraviolet rays, a superhydrophilic effect appears in the protective layer (titanium oxide layer) 3 and the tube wall Since the wettability of the surface of 2a is drastically improved, as compared with FIG. 16 (a), the pipe friction resistance is reduced and the flow velocity on the surface of the pipe wall 2a is remarkably increased as shown in FIG. 2 (a). Heat exchange performance is improved. Even if the cross-sectional area of the flow path is reduced in order to further improve the heat exchange performance, the pipe friction resistance on the surface of the pipe wall 2a is sufficiently low. Compared to FIG. 16 (b), FIG. ), The flow rate is sufficiently high and the heat exchange performance is large.

The amount of heat exchange increases due to the improvement of the superhydrophilic effect in this way because the cooling water 900 almost contacts the minute irregularities on the surface of the tube wall 2a as shown in FIG. 2 (c). This is because heat radiation from the entire surface 2a becomes possible.
Since the hydrophilicity of the surface of the tube wall 2a is improved by the protective layer (titanium oxide layer) 3, the tube friction resistance is remarkably reduced, the cooling water speed near the tube wall 2a is increased, and the cooling performance is improved. As a result, the responsiveness is dramatically improved when the LD array 200 is energized, and the transmission wavelength of the LD array 200 can be instantly stabilized.
Moreover, since the pipe friction resistance of all the pipe walls 2a of the flow path 2 in the radiator 1 can be greatly reduced, it is possible to reduce the pressure loss.

  Then, the detail of the structure of this heat radiator 1 is demonstrated roughly. FIG. 3 is a cross-sectional view of the radiator taken along the line P-P. 4 is a cross-sectional view of the radiator, FIG. 4 (a) is a cross-sectional view taken along the line A-A, FIG. 4 (b) is a cross-sectional view taken along the line BB, and FIG. 4 (c). These are C arrow directional views of a CC line cross section.

The radiator 1 is a radiator for a high-power LD array, and employs a three-layer structure in which a plate-like lower heat receiving body 10, a middle heat receiving body 20, and an upper heat receiving body 30 are stacked as shown in FIG. ing. The lower heat receiving body 10, the middle heat receiving body 20, and the upper heat receiving body 30 are all manufactured using a metal material having good heat conduction. These lower heat receiving body 10, middle heat receiving body 20, and upper heat receiving body 30 are each provided with a through hole (for example, circular communication port 22 of middle heat receiving body 20), a bottomed hole (for example, lower surface water channel 13 of lower heat receiving body 10), or A flow path forming surface such as a flat surface (for example, a flat surface of the upper heat receiving body 30 on which the protective layer 34 is formed in contact with the through hole 24 of the intermediate heat receiving body 20) is formed, and titanium oxide is formed on these flow path forming surfaces. A protective layer 3 as a layer is formed. Other than this flow path forming surface, it is a joint surface on which ground metal appears.
The lower heat receiving body 10 includes a water supply port 11, a heat radiating fin 12, a lower surface water channel 13, a flow path, as shown in the top view of the lower heat receiving body 10 viewed from the direction of arrow C as shown in FIG. 3 and FIG. The throttle part 14 and the drain port 15 are provided. The stippled portion is a hole with a bottom and represents that the protective layer 3 is formed.
The intermediate heat receiving body 20 has a circular communication hole 21, a circular communication hole 22, a partition wall 23, a penetrating hole as shown in the top view of the intermediate heat receiving body 20 as viewed from the direction of arrow B as shown in FIG. 3 and FIG. A hole 24, an upper counterbore part 25, and a lower counterbore part 26 (see FIG. 3) are provided. The stippled portion is a hole with a bottom and represents that the protective layer 3 is formed.
As shown in FIG. 3 and the bottom view of the upper heat receiving body 30 as viewed from the direction of arrow A as shown in FIG. 34 is provided. The dotted portion of the upper surface water channel 32 indicates that the protective layer 3 is formed with a hole with a bottom, and the mesh portion of the protective layer 34 indicates that only the protective layer is formed on a plane, not a hole. Yes.

These lower heat receiving body 10, middle heat receiving body 20, and upper heat receiving body 30 are bonded and laminated by a bonding layer that bonds the bonding surfaces to each other, and a flow path as shown in FIG. 3 is formed.
Although not shown, this bonding layer is a layer formed by electrically, thermally, and mechanically bonding the bonding surfaces of the heat receiving bodies by brazing, a brazing material sheet, or diffusion bonding. The brazing material is used for materials that cannot be welded, such as copper. Place the brazing material (copper and gold, or an alloy of copper and silver) in a vacuum furnace and connect it to a soldering furnace. Melt the material and connect. Thereby, it becomes the heat radiator 1 formed integrally. Diffusion bonding is performed by applying heat in a state where the lower heat receiving body 10, the middle heat receiving body 20, and the upper heat receiving body 30 are sandwiched and pressed by a press. The radiator 1 is configured in this way.

In the radiator 1 of this embodiment, since the protective layer 3 is formed in the flow path 2, electrical insulation is ensured between the cooling water and the electrolytic corrosion is prevented.
Furthermore, if the protective layer 3 is the titanium oxide layer 3, the pipe friction resistance of all the flow path forming surfaces in the radiator 1 can be greatly reduced, and the pressure loss can be reduced. As shown in FIG. 4 and FIG. 14, the diameter of the circular communication port 22 is reduced so that the partition wall 23 and the radiating fins 12 and 33 of the radiator 1 and the prior art radiator 100 of FIG. The number can be increased, and the contact area with the cooling water 900 can be greatly increased to enhance the cooling effect.

Next, the flow of the cooling water 900 in the radiator 1 having such a configuration will be described.
As shown in FIG. 1, an LD array 200 is bonded to the end portion of the upper surface of the radiation fin 1. As shown in FIGS. 1, 3, and 4, the cooling water 900 guided to the water supply port 11 of the lower heat receiving body 10 passes through the circular communication port 21 of the middle heat receiving body 20 as it is, It reaches the water supply port 31 of the heat receiving body 30.
The upper surface water channel 32 of the upper heat receiving body 30 is a channel whose area is enlarged, and the cooling water 900 is enlarged in area and reaches the radiation fins 33. At this time, in order to reduce the pressure loss on the water supply side, the upper counterbore 25 is provided in the middle heat receiving body 20 just before the heat radiation fin 33 to enlarge the cross-sectional area of the flow path, and the cooling water 900 flows into the heat radiation fin 33. At this time, the heat exchange efficiency is improved by increasing the flow rate.
The cooling water 900 that has reached the radiating fins 33 is heat-exchanged between the radiating fins 33 and the cooling water 900 by the high heat of the LD array 200 and the low heat of the cooling water 900, passes through the circular communication port 22 of the intermediate heat receiving body 20, It passes between the radiation fins 12 provided in the heat receiving body 10 and reaches the lower surface water channel 13. Here, the cooling water 900 is divided into two by the flow restrictor 14, merged again at the drain port 15, and discharged to the outside of the radiator 1. At this time, in order to reduce the pressure loss, the lower counterbore 26 (see FIG. 3) is provided on the intermediate heat receiving body 20 on the rear side of the radiating fins 13 to enlarge the flow path cross-sectional area. Similarly, in order to reduce the pressure loss of the drain port 15, a through hole 24 is provided in the intermediate heat receiving body 20 to increase the flow path cross-sectional area.

In the radiator 1, the radiating fins 33 are characterized in order to enhance the cooling effect. The heat radiating fins 33 of the radiator 1 are provided below the position where the LD array 200 is attached. The heat generated in the LD array 200 is radiated by the upper heat receiving body 30 and thermally conducted in the plate thickness direction. The heat radiating fins 33 are designed to have a length several times that of the radiating fin 33.
Further, since the heat radiation amount is not sufficient only by the heat radiating fins 33 provided on the upper heat receiving body 30, heat conduction is performed to the partition wall 23 of the middle heat receiving body 20, and heat conduction is further performed to the heat radiation fins 12 provided on the lower heat receiving body 10. The structure increases the amount of heat.
It should be noted here that, as described above, the pipe friction resistance of the wall surfaces 2a of all the flow paths 2 in the radiator 1 is greatly reduced to be more circular than the conventional radiator 100 (see FIG. 14). The tube diameter of the communication port 22 can be reduced, the mounting density of the radiation fins 12 and 33 can be increased, and greater heat transfer performance can be obtained.

In such a radiator 1, since the protective layer 3 of the tube wall 2a of the flow path 2 of the radiator 1 is electrically insulated and ions do not dissolve in the cooling water 900, electricity does not flow, and corrosion due to electrolytic corrosion occurs. Does not occur. In addition, since the joints of the lower heat receiving body 10, the middle heat receiving body 20, and the upper heat receiving body 30 constituting the radiator 1 are obtained by electrically and thermally bonding the base metal, good electrical and thermal conductivity can be obtained. Therefore, it is possible to easily energize a semiconductor component or a semiconductor laser.
Further, when the protective layer 3 is a titanium oxide layer, the affinity is improved, so that the cooling performance is also improved. Therefore, the protective layer 3 can be applied to a high output LD.

  Then, the manufacturing method of the heat radiator 1 is demonstrated. Here, the reason why the silicon wet etching technique is applied as a method for forming the protective layer 3 by forming the titanium oxide of the present invention in the flow path of the radiator will be described with reference to the drawings. FIG. 5 is an explanatory view of sputtering, FIG. 5 (a) is an explanatory view of sputtering film formation, and FIG. 5 (b) is an explanatory view of a protective layer formed. FIG. 6 is an explanatory view of sputtering mask film formation, FIG. 6 (a) is an explanatory view of sputtering, and FIG. 6 (b) is an explanatory view of a deposited protective layer.

There are methods for forming titanium oxide in the flow path, such as a dipping method and spray coating, but none of them has a low reliability because the film thickness cannot be reduced and the adhesion strength is low. Therefore, a PVD method such as sputtering or a CVD method is effective as a method for forming a dense film and having high adhesion strength. However, as shown in FIG. 5A, when sputtering is performed by placing a target (titanium oxide: TiO ₂ ) 41 on the sputtering apparatus 40 without a mask, the flow path forming surface 42 and the bonding surface 43 are included. Titanium oxide is deposited on the entire surface. Since the surface of titanium oxide is an electrically insulating layer, when diffusion bonding is performed as shown in FIG. 5B, the bonding temperature becomes very high, and at the same time, the heat receiving bodies are electrically insulated. Some kind of energization method is required, resulting in a complicated structure and associated cost increase.

  As a means for solving this type of problem, when sputtering is performed as shown in FIG. 6A, the joint surfaces of the lower heat receiving body 10, the middle heat receiving body 20, and the upper heat receiving body 30 are not formed. Titanium oxide is not formed as the film portion 45. However, the mask 44 is usually processed into a mask 44 by processing a predetermined slit width on a metal plate material. However, since the processing accuracy is limited, the mask 44 is processed to be slightly larger than the width of the bonding surface of each heat receiving body. Titanium oxide is not deposited.

  In this case, as a feature of sputtering, the ionized Ar gas is blown onto the titanium oxide lump as the target 41, and the titanium oxide repelled by argon is linearly blown to the heat receiving body. Films cannot be formed on inclined surfaces. Since the portion where titanium oxide cannot be formed is in direct contact with the cooling water, the metal ions are dissolved in the cooling water by electrolytic corrosion. As a means for solving such a case, there is an ion plating method. According to this method, there is a technique capable of forming a film on an inclined surface or the like. However, since the heat receiving body at the time of sputtering is placed on the mask and the mask is not completely adhered to the bonding surface, There is also a problem that titanium oxide enters the gap, and some measures are required for forming a protective layer with an insulating film on the heat receiving body, and only on the flow path formation surface by using the silicon wet etching technology of the present invention. It became possible to form a film completely.

Then, the manufacturing method of the heat sink using the heat receiving body formed using the wet etching technique of silicon is demonstrated. 7 and 8 are explanatory views for explaining a method of forming a heat receiving member, FIG. 9 is an explanatory view of a protective layer (titanium oxide layer), and FIG. 9A is a view showing a protective layer on the side surface of the flow path. 9 (b) is a view showing a protective layer having an inner curved surface.
It is necessary to expose the ground metal on the joining surface of the heat receiving body and form a protective layer (titanium oxide layer) only on the flow path forming surface. A method for forming such a protective layer will be described. Here, the lower heat receiving body 10 will be described as an example of the heat receiving body, and a titanium oxide layer will be described as an example of the protective layer. The lower heat receiving body 10 having a flow path forming surface and a joint surface other than the flow path forming surface is formed in advance (heat receiving body forming step).

Step 1) As shown in FIG. 7A, a mask film 51 is applied to the entire surface of the lower heat receiving body 10. For example, aluminum (Al) or the like is used. (Mask film (Al) coating process)
Step 2) As shown in FIG. 7B, a resist 52 is applied only on the mask film 51 on the flow path forming surface. In this case, it is applied three-dimensionally along the inclined surface of the flow path forming surface. (Resist application process)
Step 3) As shown in FIG. 7C, a mask 53 patterned on the glass substrate is placed and exposed. In the slit 53a without patterning, light is transmitted and the resist on the bonding surface is exposed, and in the mask 53 with patterning, the light is shielded and the resist on the flow path forming surface is not exposed (resist exposure step).
Step 4) As shown in FIG. 7D, the resist 52 is developed and the exposed resist is cured to leave the resist on the bonding surface 43, and the unexposed resist 52 is peeled off (patterning development step). .

  In Steps 3 and 4 described above, a negative photoresist in which the exposed portion remains after development is used, but a positive photoresist in which the unexposed portion remains as an image may be used instead. In this case, in the patterning of the mask in step 3, light is transmitted and the resist on the flow path forming surface is exposed, and in the mask 53 with patterning, the light is shielded and the resist on the bonding surface is not exposed. In step 4, the resist 52 is developed to harden the resist that has not been exposed, and the exposed resist 52 is peeled off. Even in this way, the present invention can be implemented.

Step 5) When etching is performed, the mask film 51 on the lower side of the cured resist 52, that is, on the bonding surface of the lower heat receiving body 10, remains as shown in FIG. The mask film is removed and only the ground metal portion of the flow path forming surface is exposed (mask film etching process).
Step 6) The resist is peeled and the state other than the flow path forming surface of the lower heat receiving body 10 is covered with the mask film 51 as shown in FIG. 8B (resist peeling step).
Step 7) Sputtering is performed on the lower heat receiving body 10 and, as shown in FIG. 8C, the entire surface including the ground and the mask film 51 on the flow path forming surface of the lower heat receiving body 10 is oxidized by sputtering. A titanium oxide film 54 is formed by depositing titanium (titanium oxide film forming step).
Step 8) Finally, the entire mask film 51 is peeled off. The titanium oxide film 54 formed on the bonding surface 43 is removed cleanly together with the mask film 52, and is completely oxidized up to the boundary edge portion between the bonding surface and the channel forming surface (the channel inclined surface in FIG. 8D). A protective layer (titanium oxide layer) 55 made of titanium is formed (mask film peeling step).
As a result, as shown in FIG. 8D, a heat receiving body in which the protective layer (titanium oxide layer) 55 is provided only on the flow path forming surface is formed. Since the joint surface 43 is a ground metal, it can be easily joined by diffusion joining or the like.

  Note that, in principle, sputtering cannot form a film on a vertical portion or an inwardly curved portion, and therefore the communication holes 22 of the middle heat receiving body 20 and the bottomed holes of the lower heat receiving body 10 and the upper heat receiving body 30 shown in FIG. When the lower surface water channel 13 and the upper surface water channel 32 are formed by etching or the like, the film is not formed on the vertical portion or the curved portion in principle by sputtering. Therefore, the film can be formed by either PVD method or CVD method as typified by ion plating. Accordingly, as shown in FIG. 9A, for example, the side surface of the circular communication port 22 of the middle heat receiving body 20, the lower surface water channel 13 of the bottomed hole of the lower heat receiving body 10 and the upper heat receiving body 30 of FIG. A protective film is also formed on the inner curved surface of the upper surface water channel 32.

Subsequently, the lower heat receiving body 10, the middle heat receiving body 20, and the upper heat receiving body 30 are bonded together. FIG. 10 is a cross-sectional view of the radiator, FIG. 10A is a view taken along the line Q-Q before joining, and FIG. 10B is a view taken along the line Q-Q taken along the line Q-Q after joining. is there.
A protective layer (titanium oxide layer) 55 formed by sputtering sandwiches a brazing material sheet (not shown) with respect to the lower heat receiving body 10, the middle heat receiving body 20, and the upper heat receiving body 30 provided on the flow path forming surface. By means of diffusion bonding or soldering, bonding is performed in a state where airtightness is maintained and heat conduction is good as shown in FIG. A protective layer made of titanium oxide is not formed on the bonding surface, and the base metals can be bonded to each other more firmly. In addition, since there is no electrical insulating layer, the heat conduction and the formation of the electrical path are reliably performed.

  Such a radiator can be variously modified. For example, in order to increase the heat exchange amount, the cooling water is reciprocated inside the intermediate heat receiving body 20 as shown in FIG. However, the pipe frictional resistance is greatly reduced by the principle described above, so that the cooling performance can be further improved due to the improvement of wettability, and the cooling water circulation device can be downsized.

According to the present invention, it is possible to easily form the insulating layer only in the water channel inside the radiator by forming the titanium oxide film by using the mask film forming of the wet etching of silicon. Thereby, since cooling water and the ground metal of a radiator do not contact directly, even if a big electric field is applied to LD array, the metal ion outflow into the cooling water by electrolytic corrosion can be suppressed.
In addition, when bonding each heat receiving body, since titanium oxide is not formed on the bonding portion of the heat receiving body by using a silicon wet etching mask film forming, diffusion bonding as in the prior art It becomes possible to join easily using. Ni or Au plating or the like is applied to the heat receiving body, and bonding with AuSn solder or the like is also possible.
Further, since there is no titanium oxide layer at the joint, it is possible to conduct electricity as well as this part as in the conventional device, and there is an advantage that heat diffusion into the radiator is also good. In addition, since titanium oxide is resistant to corrosion, there is a merit that it can be applied even with general tap water.

1 is a schematic system configuration diagram of an LD array heat dissipation system including a heatsink of the best mode for carrying out the present invention. FIG. 2A is a schematic diagram showing a flow state when cooling water is passed through a flow channel in which a titanium oxide layer is formed on a tube wall, and FIG. 2A is a schematic diagram of a flow channel cross-sectional area, FIG. ) Is a schematic diagram of a small channel cross-sectional area, and FIG. 2C is an enlarged view of a tube wall. It is PP line sectional drawing of a heat radiator. 4A is a cross-sectional view of the radiator, FIG. 4A is a cross-sectional view taken along the line A-A, FIG. 4B is a cross-sectional view taken along the line B-B, and FIG. It is C arrow line view of a C line cross section. FIG. 5A is an explanatory view of sputtering, FIG. 5A is an explanatory view of sputtering film formation, and FIG. 5B is an explanatory view of a protective layer formed. FIG. 6A is an explanatory view of sputtering mask film formation, FIG. 6A is an explanatory view of sputtering, and FIG. 6B is an explanatory view of a protective layer formed. It is explanatory drawing explaining the formation method of a heat receiving body. It is explanatory drawing explaining the formation method of a heat receiving body. It is explanatory drawing of a protective layer (titanium oxide layer), Fig.9 (a) is a figure which shows the protective layer of a flow-path side, FIG.9 (b) is a figure which shows the protective layer of an inner side curved surface. FIG. 10A is a cross-sectional view of the radiator, and FIG. 10A is a view taken along the line Q-Q before joining, and FIG. 10B is a view taken along the line Q-Q after joining. It is a cross-sectional block diagram of the heat radiator of another form. It is a typical system block diagram of LD array heat dissipation system. It is PP line sectional drawing of a heat radiator. 14A is a cross-sectional view of the radiator, FIG. 14A is a cross-sectional view taken along the line A-A, FIG. 14B is a cross-sectional view taken along the line B-B, and FIG. It is C arrow line view of a C line cross section. FIG. 15A is a cross-sectional view of the radiator, FIG. 15A is a view taken along the Q-Q line before joining, and FIG. 15B is a view taken along the Q-Q line taken after joining. FIG. 16A is a schematic diagram illustrating a flow state when cooling water is passed through a flow channel in which the background of the pipe wall is exposed. FIG. 16A is a schematic diagram of a cross-sectional area of the flow channel, and FIG. FIG. 16C is a schematic view of a small road cross-sectional area, and FIG. It is explanatory drawing explaining the influence by electric power application, FIG. 17 (a) is a time-power diagram, FIG.17 (b) is explanatory drawing explaining the relationship between electric power and temperature.

Explanation of symbols

1: Radiator 2: Flow path 2a: Tube wall 3: Protective layer 10: Lower heat receiving body 11: Water supply port 12: Heat radiation fin 13: Lower surface water channel 14: Channel throttle 15: Drain port 20: Medium heat receiving body 21: Circular communication hole 22: Circular communication hole 23: Partition wall 24: Through hole 25: Upper counterbore part 26: Lower counterbore part 30: Lower heat receiving body 31: Water supply port 32: Upper surface water channel 33: Radiation fin 34: Protective layer 40: Spatter Device 41: Target 42: Flow path forming surface 43: Bonding surface 44: Mask 45: Undeposited portion 51: Mask film 52: Resist 53: Mask 53a: Slit 54: Titanium oxide film 55: Protective layer (titanium oxide layer)
200: LD array 300: Electric power supply device 400: Manifolds 400a and 400b for water supply / drainage: Channel 500: Channel 600: Tank 700: Channel 800: Pump 900: Cooling water

Claims (6)

In a liquid-cooled radiator in which a heating element is attached in contact with the outside and the heating element is cooled by a coolant flowing through a flow path formed on the inside,
A protective layer that covers the flow path forming surface inside the radiator and electrically insulates the coolant from the radiator,
A heat radiator characterized by comprising. The heat radiator according to claim 1,
The radiator is a titanium oxide layer that is electrically insulated and reduces frictional resistance. The heat radiator according to claim 1 or 2,
The heat radiator is a laser diode array on which a semiconductor laser diode that electrically connects the heat radiator as a part of a power supply path is mounted. In the heat radiator as described in any one of Claims 1-3,
The radiator is
A plate-shaped heat receiving body having a flow path forming surface on which a protective layer is formed, and a joint surface on which a ground metal appears other than the flow path forming surface;
A bonding layer bonded at the bonding surface of these heat receivers;
A heat radiator having a structure in which a plurality of heat receiving bodies are joined and laminated by a joining layer, and a flow path covered with a protective layer is formed. The heat radiator according to claim 4,
The radiator is a radiator formed by joining the joining surfaces of the heat receiving bodies electrically, thermally and mechanically by brazing, brazing sheet or diffusion bonding. A method for forming a heat receiving body constituting the radiator according to claim 4,
A heat receiving body forming step of forming a heat receiving body having a flow path forming surface and a joint surface other than the flow path forming surface;
A mask film coating process for coating a mask film on the entire surface of the heat receiver;
A resist coating step of coating a resist on the mask film on the surface including the flow path forming surface;
A resist exposure step of placing a mask on the resist and exposing the resist on the bonding surface;
A patterning development step of developing the resist and peeling off the resist on the flow path forming surface;
A mask film etching step for removing the mask film on the flow path forming surface and exposing the metal on the flow path forming surface;
A resist stripping process for stripping all resists;
A film forming step of forming a film on a surface including a flow path forming surface by a PVD method such as sputtering or ion plating, or a CVD method;
A mask film peeling step for peeling the mask film and forming a protective layer only on the flow path forming surface;
A method of forming a heat receiving body, comprising:

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